The Borrelli outlet store (near the Vatican) in Rome unfortunately is no more. They attracted the wrong crowd I was told, whatever that may mean. The Borrelli store itself however is and prices are lower than in the US or elsewhere in Europe (especially if you are able to reclaim the Italian VAT). Borrelli store is very small and in a small side street of the Via Condoti and a 2 minute walk from the Spanish steps. Right around the corner (and on the same square as Spanish steps) is the Kiton shop. Never has sale and prices are always giving me the hickups. Boggi is in the same street (5 minute walk from Spanish steps) in the direction of the Obelisk (I forgot the corect name of the Piaza).
Borrelli is also sold in a store called Cosimo Colonne (right around the corner of Davide Cenci referred to a few posts above). They used to have Attolini and a very nice qualifty house brand too.
If you really want to visit sartorial paradise go to The White Gallery (its about a 35 minutes busride from Termine Station but you will be flabergasted). Kiton, Attolini, Sartoria Partenopea, Cucinelli, Santoni, Lobb. Bring you lady and she will likely spend hours on the first floor. Address: